Clinical value of FDG-PET/CT in suspected occult cancer

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Abstract

AIM Patients with clinically suspected occult cancer are a heterogeneous group
presenting with a multitude of non-specific symptoms. Confirming or refuting a
malignant diagnosis is of paramount importance and a multitude of diagnostic
modalities are often employed. Due to an increased use of FDG-PET/CT in these
patients at our institution, we performed a retrospective survey of a consecutive
series referred to FDG-PET/CT for suspected occult cancer. MATERIAL AND
METHODS All patients referred from our hospital during a 2-year period with
clinically suspected occult cancer were included. A comprehensive retrospective
chart review provided dates and conclusions of all diagnostic procedures and
events during a mean follow-up period of 23 months [range 1-36]. Follow-up was at
least 12 months in all patients without cancer. A PET/CT scan was considered true
positive for cancer, if an increased focal FDG uptake suggestive of malignancy was
confirmed by biopsy, and false positive if subsequent investigations could not
confirm malignancy during follow-up. A scan was considered true negative, if a
normal FDG uptake or an abnormal FDG uptake were reported as reflecting a
benign condition, and no malignant disease was found during follow-up, whereas a
scan was considered false negative, if no abnormal FDG uptake suggestive of
malignancy was reported, and a cancer was diagnosed during follow-up. RESULTS
Our series comprised 99 patients, 50 females and 49 males with a mean age of 66
years [range 26-90]. PET/CT was suggestive of cancer in 30 patients (17 true
positive, 13 false positive), and showed no cancer in 69 patients (66 true negative,
3 false negative). Thus, the sensitivity, specificity, accuracy, positive and negative
predictive values were 85% [61%-95%], 84% [73%-90%], 84% [73%-90%], 57%
[38%-74%], and 96% [87%-99%], respectively (95% confidence intervals in
brackets). CONCLUSION FDG-PET/CT showed a high diagnostic yield with a very
high negative predictive value in this consecutive, unselected and heterogeneous
group of patients with clinically suspected occult cancer. Thus, FDG-PET/CT should
be at the forefront of the diagnostic workup in this category of patients.
Original languageEnglish
Article numberP336
JournalEuropean Journal of Nuclear Medicine and Molecular Imaging
VolumeVolume 40
Issue numberSuppl. 2
Pages (from-to)381
ISSN1619-7070
Publication statusPublished - 2013

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